1. Field of the Invention
The invention relates to a wastewater treatment device and its applications as well as a wastewater treatment method using the same, and more particularly to an integrated bioreactor and its applications as well as a method for treatment of highly-concentrated organic wastewater using the same.
2. Description of the Related Art
Upflow anaerobic sludge blanket technology, normally referred to as UASB, has been widely used in treatment of industrial wastewater recently. UASB mainly operates under intermediate temperature (30-35° C.) and high temperature (50-55° C.), resulting in ideal effluent quality because of excellent microbiological activity inside the reactor. However, when temperature is low, the microbiological activity in a UASB will be restrained. Once organic loading is higher, acid-base equilibrium inside the UASB reactor is likely to be acidified, leading to higher chemical oxygen demand (COD) concentration, acidic effluent pH level, and upward-flow of sludge, consequently the effluent quality will be severely deteriorated.
To ensure stable operation of UASB under low temperature and maintain acid-base equilibrium inside the UASB reactor and avoid acidification, different measures can be adopted such as heating up wastewater, adding alkalinity, effluent recycle, recycle after CO2 stripping, or adding low-temperature bacterial strain. Nevertheless, in actual technical applications, all those measures have disadvantages and limits, e.g. high economic cost, large energy consumption, too many dissolved oxygen in effluent, and absence of application examples.
Integrated bioreactors combine a variety of biological treatment processes within a single bioreactor to deal with wastewater, having the advantages of low investment, low land occupation, low energy consumption, excellent treatment results, and convenient management. Until now, there have been a large number of studies and applications on integrated bioreactors used in treatment of domestic sewage and industrial wastewater by systematically integrating anaerobic, anoxic, and aerobic processes within a superimposed or a sleeve type reactor. However, those integrated reactors are only used under normal temperature. There is no R&D on integrated bioreactors used in treatment of highly-concentrated organic wastewater under low temperature conditions.
Moving bed biofilm reactor (MBBR) is a new and efficient aerobic wastewater treatment process based on conventional activated sludge process and biological contact oxidation process. MBBR process, using suspended carriers with specific gravity close to water as microbial carriers, enables microorganism to fully contact with dissolved oxygen and organic substances within the water by means of powerful lifting effect of aeration and water current. Such process is in favor of transferring matrices to achieve excellent removal effect on organic substances. Compared with other aerobic wastewater treatment processes, MBBR process has the advantages of lower land occupation, stronger load impact, higher sludge concentration, fewer surpluses sludge volume, less head loss, and excellent nitrogen and phosphorus removal effects. It also does not need backwash or recycling. In addition, many studies have shown that since sludge concentration is high and biosolids have long retention time under MBBR process, it can still achieve an ideal effect even under low temperature conditions.